The social impacts of the project concern mostly the surrounding local communities (both indigenous and non-indigenous). These implications range from health issues, destruction of local environment, contamination of water, implications on farm production, possible destruction on local indigenous artefacts, concerns for local economies in case of a leak in the pipeline, and much more.

For example:

• In 2007, Alberta's government approved the withdrawal of 119.5 billion gallons of water for tar sands extraction. An estimated 82% of this water comes from the Athabasca River. Toxic wastewater is discharged in holding or tailing ponds that now leak 11 million litres of toxic waste per day into the Athabasca and seep into the ground water. This water flows northward (downstream) further into Indigenous territories. Since this toxic waste has been flowing into the river and seeping into the groundwater, rare and virulent cancers have affected many of the Indigenous Community members, and fish and game have been found with physical abnormalities, deformations and tumors.
• This is also a concern for other communities along the path as the pipeline crosses large water reserves. If there was a leak there could be contamination in drinking water for millions of Americans and devastate the mid-western U.S. economy.

There are various levels of concern for the environment, from the original stages of production, to the processing and transportation of the oil.

For example:

• The toxic waste run off has had detrimental effects on the surrounding environment. In short, the pipeline could pollute air and water supplies and harm migratory birds, fish, and other wildlife.
• The path of the pipeline crosses the Sanhills of Nebraska, which is the largest wetland ecosystem in the United States, as well as the Ogallala Aquifer, which is one of the largest reserves of fresh water in the world.
• Some of the pipeline will also cross an active earthquake zone with a magnitude of 4.3 as has happened in 2002. It is argued that TransCanada applied to the U.S. government to use thinner steel and pump at higher pressures than normal. Meaning, a leak is not out of the question. More information.
• At the same time, in order to expand production capacity in the Tar Sands, Exxon is seeking permission to haul 200 loads of equipment from Port of Lewiston, ID, along the LoLo Pass to Missoula, MT, with the final destination of the Tar Sands. These shipments are 24 feet wide, 30 feet tall, and up to 262 feet long, weighing up to 500,000 pounds. Many upgrades will be necessary to follow through with this plan as the current route runs through a delicate ecosystem on an unprepared roadway. These transformations would include relocating power and telephone lines, widening and strengthening banks, curves and the road base.

A July 2017 Greenpeace report concluded: oil spills anywhere pose serious risks to human health and the environment, and oil spilled into bodies of water is difficult to fully clean up. Diluted bitumen transported from Canada’s tar sands fields represents a particular threat to water resources along the routes of proposed pipelines.

As stated by Francois Paulette of the Smith's Landing Treaty 8 First Nation of the Northwest Territories: "White House policy makers need to know that their appetite for this dirty oil is killing our river and destroying our way of life. The pollutants and heavy metals don't stop at the Alberta border - they run more than 1,000 kilometres all the way to the Mackenzie River, deforming the fish along the way."

There has been much opposition from indigenous groups from both Canada and the U.S. So much that groups from both countries have joined forces to oppose the project together. According to the Toronto star, there is almost unanimous opposition to the pipeline among tribal communities living close to the proposed pipeline's U.S. route.

Amongst the various health and environmental concerns, another major concern is that the project will disrupt and/or destroy traditional native burial sites in the Sandhills region of Nebraska. Under U.S. law, any such disturbance disqualifies such sites from future inclusion in the National Historic Registry. Full article here.